flutter-go/packages/flutter_web/test/rendering/dynamic_intrinsics_test.dart

// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter_web/rendering.dart';
import '../flutter_test_alternative.dart';

import 'rendering_tester.dart';

class RenderFixedSize extends RenderBox {
  double dimension = 100.0;

  void grow() {
    dimension *= 2.0;
    markNeedsLayout();
  }

  @override
  double computeMinIntrinsicWidth(double height) => dimension;
  @override
  double computeMaxIntrinsicWidth(double height) => dimension;
  @override
  double computeMinIntrinsicHeight(double width) => dimension;
  @override
  double computeMaxIntrinsicHeight(double width) => dimension;

  @override
  void performLayout() {
    size = Size.square(dimension);
  }
}

class RenderParentSize extends RenderProxyBox {
  RenderParentSize({RenderBox child}) : super(child);

  @override
  bool get sizedByParent => true;

  @override
  void performResize() {
    size = constraints.biggest;
  }

  @override
  void performLayout() {
    child.layout(constraints);
  }
}

class RenderIntrinsicSize extends RenderProxyBox {
  RenderIntrinsicSize({RenderBox child}) : super(child);

  @override
  void performLayout() {
    child.layout(constraints);
    size = Size(child.getMinIntrinsicWidth(double.infinity),
        child.getMinIntrinsicHeight(double.infinity));
  }
}

void main() {
  test('Whether using intrinsics means you get hooked into layout', () {
    RenderBox root;
    RenderFixedSize inner;
    layout(
        root = RenderIntrinsicSize(
            child: RenderParentSize(child: inner = RenderFixedSize())),
        constraints: const BoxConstraints(
            minWidth: 0.0,
            minHeight: 0.0,
            maxWidth: 1000.0,
            maxHeight: 1000.0));
    expect(root.size, equals(inner.size));

    inner.grow();
    pumpFrame();
    expect(root.size, equals(inner.size));
  });
}